1. Field of the Invention
This invention relates to a method for preparing visually clear, stable aqueous citrus flavored mouthwash compositions in a procedure which reduces flammability hazards associated with mixing volatile alcohols and eliminates the necessity of certain equipment.
2. The Prior Art
Consumers desire pleasant tasting mouthwash. Mint, fruit or spice-type flavors are readily solubilized into mouthwash formulations. A wide spectrum of emulsifiers are available for obtaining stable clear emulsions with these types of flavors. Citrus flavors, however, have proven difficult to formulate with mouthwashes. Insolubility and/or emulsion instability are frequently encountered.
When citrus oil flavors are used in mouthwashes, the compositions frequently become cloudy. Also, a settling-out of certain components during storage often occurs. These undesirable properties have been ascribed to the presence of non-polar terpene components in citrus oil.
Only a limited number of emulsufiers are known that readily solubilize sufficient amounts of citrus oils to yield end products with recognizable citrus flavor. A further restriction is the requirement that only food grade additive emulsifiers be employed. Safe additives are required in view of the possibility of accidental ingestion.
Conventionally, mouthwash products are formulated by mixing emulsifiers, flavor materials and other alcohol-soluble components with alcohol in a suitable mixing apparatus. Water and water-soluble components are then added to the mixing apparatus containing the alcohol solution. The entire contents are then blended to form the final mouthwash product. U.S. Pat. No. 3,639,563 is a typical disclosure of the conventional method.
A method for specifically preparing clear lemon-flavored mouthwash is described in U.S. Pat. No. 3,876,759. Therein, a premix of lemon oil, emulsifier and alcohol are first formed. Subsequently, the alcoholic emulsified lemon oil premix is added to a water solution held in a second mixing tank. Clear stable liquid products are claimed to result from this process.
The aforementioned patents have instructed on the necessity of delivering emulsified flavor first into an alcohol vehicle prior to mixing with water. The flammability hazard associated with separately mixing alcohol and emulsifier can be eliminated with the present invention. Blending equipment need therefore not be fitted with expensive explosion proof electrical motors and other similar safety apparatus. Furthermore, premix equipment also becomes unnecessary where ethanol and emulsifier no longer need be blended together.
Besides clarity and stability, emulsifiers must have acceptable taste properties. Nonionic emulsifiers are known for imparting flavor notes (bitter or sour overtones) to mouthwashes. Flavor oils are not always successful at masking those notes, especially in blends containing modest amounts of flavor oil.
U.S. Pat. No. 3,639,563 provides a solution to the taste problem. Small amounts of chloroform are added to alcohol-nonionic emulsifier containing aqueous mouthwash. Superior taste characteristics are imparted. Unfortunately, chloroform is a suspected carcinogen. Its use in oral applications has been thereby circumscribed.
It is an object of the present invention to disclose a method for preparing clear, stable citrus flavored mouthwash products.
Another object of this invention is to obtain a clear, stable citrus flavored mouthwash by a method that minimizes the flammability hazard of handling ethanol and that reduces capital costs by requiring fewer mixing vessels.
It is a further object of this invention to identify emulsifiers that can be effectively used in the method of the present invention.
Furthermore, it is an object of the present invention to prepare citrus flavored mouthwash by an improved method comprising an emulsifier that provides not only clear, stable formulations but that also does not impart the bad flavor notes of the emulsifier.